Thursday, September 08, 2016

Blogger Jessa Gamble comments on a
recent paper that got lots of press recently. The paper, about the
migration of the ancestors of Amerindians from Asia to the Americas,
was widely misunderstood to have called this theory into question. In
fact, it did nothing of the sort. Gamble considers why this
misconception spread so rapidly:

All this became clear to
me after reading the paper, but I can see why the wrong story got
out. Though the paper is clearly titled -- "Postglacial viability and
colonization in North America's ice-free corridor" -- the press
release is vaguer: "Textbook story of how humans populated America is
'biologically unviable,' study finds". It opens: "The established
theory about the route by which Ice Age peoples first reached the
present-day United States has been challenged by an unprecedented
study which concludes that their supposed entry route was
'biologically unviable'".

If the average person knows
anything about how America was first populated, they know that people
are supposed to have crossed from Asia over a land bridge during the
Ice Age. That's probably about it. So when you tell them the
"established theory" is wrong, this is what they think
about. Confusing the Bering Land Bridge with the "ice-free corridor"
is even easier given that the latter doesn't really have a name and
the former is kind of corridor-like.

In general,
non-specialists are usually satisfied with one point about any given
topic about which they have no particular interest. If it makes sense
in their narrative of the world, it lodges into their general
knowledge in the place where curiosity might have been. Camel
humps? Something about storing water in the desert. Never mind that
they evolved to store fat for warmth in the Arctic. Michael J. Fox's
middle name? Starts with J. (It's Andrew). [bold added]

I
attribute this partly due to the fact that no one person can know
everything: Past a certain point, we have to rely on an intellectual
division of labor. But part of the problem is cultural, and pertains
to the proper way to approach expert advice, as Alex Epstein indicates
at several points in The Moral Case for Fossil
Fuels:

To be sure, we absolutely need experts. Experts
are an indispensable source of information about the state of
knowledge in specific fields -- whether economics or energy or climate
science -- that we can use to make better decisions. But we can get
this benefit only so long as the expert is clear about what he knows
and how he knows it, as well as about what he doesn't know.
(p. 27) [emphasis in original]

And this works both ways. For example, a couple of people I know take the opposite
approach to expertise, and will occasionally latch on to something
they have heard about from an "expert" and begin proselytizing. It is
astounding how many times I have gotten "advice" from them, only to
immediately find problems on a cursory internet search. And I am
always floored that they apparently don't even bother with the first
step to evaluating anything being put forth as knowledge:
Seeing how it fits in with everything else they know -- or finding
what else they might need to know before making a
judgement.

So how would this play out for an average person
hearing that "the" commonly-accepted theory about Amerindian origins had
been called into question? First of all, like experts, we should be
clear in our own minds about what we know and don't know. Such news
would challenge the premise that we know how the Americas were first
populated, but that would really just underscore that what we "knew"
came from experts in the first place, and that we would need further
investigation to understand what that meant, and whether, say, an
alternate theory was proposed. It would not, without even this
minimal level of investigation, warrant "shooting down" someone who,
in casual conversation, advanced the "old" theory.

I might
try an experiment the next time I encounter someone I know to approach
the use of experts in the wrong way. I bet, after the many times I
have challenged unquestioned "expert" wisdom, they will take pleasure
in "informing" me that I am wrong.

2 comments:

I'm still not sure how to handle expert opinions....On the one hand, experts aren't deities handing out The Truth; but on the other hand, they DO know more than the average person, so if you're going to argue with them you at least need to know more than the average high school education provides. It's a complicated topic, one I'm in no way sure of myself.

I will say that the camel thing sounds vey sketchy to me. The issue is, humps are extremely hard to study in the fossil record. For example, cave drawings show that the Irish Elk had a fairly substantial hump (not as pronounced as camel humps, but still significant), despite there being no osteological evidence for it. Soft tissue rarely survives long-term. What that means is that we can't say for certain when humps arose in camels. Tying these fossils to modern camels via biochemistry is not, in my opinion, sufficient, because this doesn't tell us when the first humps in this lineage arose. Humps could have arisen numerous times in the lineage--lizards lost their legs in multiple lineages, independently.

This isn't just an issue with camels, by the way--the question arises with dinosaurs as well. The model dinosaurs you've seen on store shelves, or pictures in books, suffer from what's called the "shrink wrap" effect: the models are reconstructed with the skin as tight to the bones as the artists can make it. A researcher once used the same methods to reconstruct a cat skeleton, with terrifying results! There are also several structures (hadrosaur crests, Spinosaurus vertebral spines, and the like) that could represent humps or hump-like features. But without soft tissue, there's simply no way to know for sure.

I want to be clear: It's a reasonable explanation. And it may well be true. I'm just not convinced that they've demonstrated that it is. It also demonstrates that "expert" is a sliding term. I may count as an expert in fossils, but I'm reasonably certain that these questions have been addressed somewhere by the authors of these reports (they were not in the reports you linked to). It's fairly common in science; we all have our niche of expertise.

Thanks for the interesting discussion about the problems of pinning down the origin of camel humps. It reminded me a little of news of an interesting recent attempt to determine the minimal genomic requirements for life, wherein the researchers had to admit that they had no idea about the function of about a third of the presumably essential genes.

Sometimes the limits of our knowledge can be almost as interesting as the knowledge itself.